Machine for grinding lenses



A. J. HOLMAN ET AL MACHINE FOR GRINDING LENSES June 6, 1950 2 Sheets-Sheet 2 ARTHUR ,J.HO| MAN WILLIAM J KENNEDY INVENTORS BYWW khviv-A'I'I'ORNEY Filed March 17, 1945 Patented June a, 1950 MACHINE FOR GRINDING LENS/ES Arthur J. Holman, Brighton, and William J. Kennedy, Rochester, N. Y., assignors, by mesne assignments, to Arthur J. Holman, Rochester,

Application March 17, 1945, Serial No. 583,214

1 Claim. (01.51-73) This invention relates to methods and machines for grinding lenses and, more particularly,"

to machines of the generating type, one object of the invention being to provide an improved method of the above character for grinding lenses with a high degree of precision and at a more rapid rate.

Another object is to provide such a method in which the lens blanks are fed toward and away from the tool by one of the generating motions, so as to facilitate the insertion and removal of the lens blanks during the continuous operation of the machine.

Another object is to produce an improved method ofthe character described comprising relative generating motions of the tool and work surfaces adapted to grind a wider variety of curved surfaces on the work.

A further object is to provide a simple and practical machine for carrying out the above method.

Still a further object is to provide an improved lens generating machine in a more practical and eflicient type of construction capable of generating lens surfaces with increased precision and at a more rapid rate of production.

To these and other Lends the invention resides in certain improvements and combinations of parts, all as will be hereinafter more fully described, the method steps and novel features being pointed out in the claims at the end the specification.

In the drawings:

Fig. 1 is a top plan view of a lens generating machine embodying the present invention;

Fig. 2 is a side elevation of the same as viewed from the right in Fig. 1;

Fig. 3 is an enlarged sectional elevation on the line lit-3a in Fig. 1, and

Fig. 4 is an enlarged fragmentary sectional view through the tool and lens surfaces, to illustrate the grinding action.

The present invention comprises a lens surface generating method in which a plurality of lens holding chucks are mounted in spaced relation about the periphery of a rotatable chuck holder, or wheel, which is slowly rotated within an annular grinding ring rotating at optimum grinding speed about an axis arranged, in the present embodiment of the invention, so as to intersect at right angles with the axis of rotation of the chuck holder. The grinding ring preferably comprises juxtaposed rough and fine grinding sections to which the lens blanks are fed one after another by the continuous rotation of the chuck holder, so that each lens blank is subjected first to rough and then to fine grinding during a single passage over the grinding ring and each lens blank with .its chuck is inserted in and removed from the chuck holder during the continuous rotation of the chuck holder. A

method steps.

The machine at present preferred for carrying out the above method comprises a circular chuck holder ID, in the general form of a; wheel having axial trunnions H mounted for rotation in a pair of arms 12 extending in spaced relation from a forked standard l3, so as to embrace the wheel therebetween. Standard I3 is stationarily supported in any suitable manner, being shown in the present instance as carried by a base It, fixed on a supporting surface l5, forming part of a machine. frame, workbench, or other suitable structure.

Chuck holder ID has a series of chuck receiving sockets it formed inits periphery in radially extending, circumferentially spaced relation as shown, eight such sockets being provided in the present instance, although it will be evident that a greater or less number may be employed. The lens holding chucks, indicated generally at l1, are preferably formed with cylindrical shanks l8, closely but slidably fitting in the sockets l6 which are enlarged at their outer ends for receiving and seating the chuck heads IS. The lens blanks 20 are mounted on the ChlliCkS by means of the usual recessed seats, as shown, or in any other suitable manner, as well understood in the art. Each chuck shank I8 is preferably formed 'with a groove 2 I for coaction with the end of a plunger 22, sliding in a bore 23, and pressed into engagement with the chuck by a compression spring 24 between the plunger and a screw plug 25 in the outer end of the bore. a The groove 2| and the plunger end are so beveled or otherwise formed that the spring actuated plunger, engagin in the groove, serves to firmly and securely hold the chuck in its socket, .while permitting it to be removed by a substantial outward pull, so that the chucks can be manually inserted in the sockets for grinding the lenses and removed therefrom after the lenses are ground, at the outer side of the wheel, during the continuous feeding rotation thereof. Means are provided for rotating the chuck holder or wheel as hereafter described.

The generating tool preferably comprises an 8 annular ring, indicated generally at 26, Figs. 3 and 4, mounted on the circular edge or rim of a frame 21. which is of hemispherical or shell shape in the present instance and is mounted for rotation about the axis perpendicular to the plane of said edge or ri-m at its center. The grinding ring preferably comprises a roughing diamond grinding section 28 and a fine milling diamond section 29, the inner periphery of the latter being of cylindrical form and of the same diameter as the cylindrical bore of the section 28,

as best shown in Fig. 4, to first rough grind and then fine grind the lens blank. The grinding sections 28 and 29 are preferably secured to the rim of the frame 21, by means of a circular plate 30 and a series of bolts 3| passing through openings in the plate and the grinding sections and threaded into the rim of the frame 21, as shown.

The particular construction of this two-section grinding ring forms no part of the present invention, being described and claimed in the copending application for patent of Arthur J. Holman, Serial No. 589,983, filed April 24, 1945.

Frame 21 is formed in the present instance concentric with its axis of rotation with an opening 32 having an inner end portion 33 of reduced diameter. A journal 34 is fixed in the opening with a shoulder 35 seated againstthe reduced portion 33 of the opening, the journal having on its inner end a nut 36 binding against the inner surface of the frame for fixedly securing the journal therein. The outer end of the journal 34 is rotatably supported in bearings in spaced arms 31 at the upper end of a forked standard 38 stationarily mounted in any suitable manner, as on the frame or support 15 for the chuck holder. A boss 39 on the frame 21 and a nut 40 on the outer end of the journal 34 engage the opposite faces of the bearing arms 31 and secure the frame against endwise play in the bearings.

Frame 21 and its annular grinding ring 28 are rotated at suitable grinding speed by means of a grooved pulley 4| fixed on journal 34 between the bearing arms 31 and driven by a belt 42. The chuck holder or wheel is rotated at a suitable speed for feeding the lenses to the grinding ring, by means of a reduction speed drive preferably comprising a worm gear 43, Fig. 2, fixed on an extended end 44 of one of the trunnions I I and driven by a worm 45, fixed on a shaft 451: driven from any suitable source of power.

The axes of rotation of the chuck holder and grinding ring, in the present embodiment for grinding convex spherical surfaces, are preferably arranged to intersect each other at right angles, the chuck holder being preferably so positioned within the grinding ring that the axis of rotation of the grinding ring lies substantially in the plane of the axes of the lens chucks, and the axis of rotation of the chuck holder lies substantially in the plane of that face of the grinding ring which is in contact with the rim of frame 21 as shown in Fig; 3, but it will be obvious to those skilled in the art that such relations may be departed from for the purpose of grinding toric or other non-spherical surfaces. Thus by varying the diameter of a chuck holder relative to its grindin ring and offsetting the axis of rotation of the chuck holder from the axis of rotation of the grinding ring or by positioning said axis at different distances from the plane of the face whereon the grinding ring is mounted on frame 21 various toric surfaces may be ground.

The method steps are evident from the operaticn of the machine as described above in connection with its construction. chuck holders and grinding rings may be employed in the machine having varying diameters selected to correspond with the particular lens surfaces to be ground. For grinding convex spherical surfaces, the parts are positioned in the described relation with the axes of rotation of the chuck holder and grinding ring intersecting at right angles and the axis of rotation of the chuck holder lying substantially in the plane of the inner face of the ring. With grinding ring and chuck holder rotating continuously at suitable grinding and work feeding speeds, respectively, the chucks carrying the lens blanks are inserted one byone in the sockets ll of the chuck holder at the exposed portion of the chuck holder or wheel as each socket moves slowly toward the grinding ring. As each lens blank passes through the grinding ring, the ring sections first rough grind and then fine grind the surface to the spherical shape generated by the combined rotary motions of the grinding ring and chuck holder. After emerging from the grinding ring, each ground lens blank with its chuck is removed from the chuck holder by the operator and is replaced by a chuck carrying another lens blank to be ground.

The chuck holder is so constructed that the chucks and the lenses mounted therein may be accurately positioned for the grinding operation, while the abrading surfaces of the grinding ring maybe readily trued up from time to time as required, and the construction generally is of such a nature as to be readily manufactured and maintained in condition for precise grinding work. The multiple arrangement of the chucks on the chuck holder and its rotary feeding movementinto and out of the diamond milling ring facilitate the loading and unloading of the chucks and their lenses without interruption of the grinding operation, so that rapid continuous production is maintained. By the employment of chuck holders and milling rings of various diameters, as well as by variations in the relation of the axes of rotation of the elements, the method and machine may be adapted for grinding a variety of curved surfaces.

It will thus be seen that the invention accom-.

plishes its objects and while it has been herein disclosed by reference to preferred details of method steps and structural parts, it is to be understood that such disclosure is intended in an illustrative, rather than a limiting sense, as it is contemplated that various modifications in the method steps and in the construction and arrangement of the machine parts will readily occur to those skilled in the art, within the spirit of the invention and the scope of the appended claim.

We claim:

In a lens surface generating machine, the com bination of a rotatably mounted grinding ring having an internal abrading surface substantially cylindrical in form, a rotatable chuck holder in the form of a wheel and having a plurality of chuck receiving sockets spaced equally around its circumference, chucks carrying lens blanks adapted to be inserted successively in said sockets at aposition exterior to said grinding ring, means for rotating said grinding ring about the axis of its internal abrading surface at suitable lens grinding speeds, and means for rotating simultaneously said chuck holder in spaced relation to said grinding ring to effect a feeding continu- Number radius or curvature equal to the radius or said 8 3 3 internal abrading surface of said grinding ring and deliver said lens blanks after grinding to a position exterior to said grinding ring.

ARTHUR J. HOLMAN.

WILLIAM J. KENNEDY. 1 ,6 3

1,901,181 REFERENCES CITED The following references are of record in the me 01 this patent: u g-, UNITED STATES PATENTS 327,311

Number Name 558,225 Barnes -1.-- Jan. 21, 1896 836,486 Conner Nov. 20, 1906 Name Date Wall et a1. May 25, 1915 Hollands Apr. 10, 1917 Taylor Dec. 27, 1921 Taylor Dec. 27, 1921 Bugbee Aug. 15, 1922 Schuessler Mar. 13, 1923 Taylor Jan. 8, 1924 Bugbee July 17,1928 Jopps Oct. 20, 1931 McCabe Mar. 14, 1933 FOREIGN PATENTS Country Date Great Britain May 12, 1894 France June 19, 1903 

